Snap action device



March 27, 1956 LAUTZENHISER SNAP ACTION DEVICE Filed Dec.

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r MM s mp w mw w L H 3 G A m .g 0. f H A 9 B 3 2 4 6 l l4 2 2 8 ll 6 6 6I 6 0 3 4 6 O 5 5 6 6 4 United States Patent SNAP ACTION DEVICE ArgyleG. Lautzenhiser, Anderson, Ind., assignor to General Motors Corporation,Detroit,.Mich., a corporation of Delaware Application December 11, 1953,Serial-No. 397,676 6 Claims. (Cl. 200-67) This invention relates to aswitch and is particularly concerned with a snap action device havingpredeterminedand adjustable-limits for'operation' in either direction.

Specifically it is an object of the invention to provide a pressureoperated switch having a snap action mechanism therein which includesadjustments for independently varying the pressure at which the switchopens and closes.

A further object of the invention is to provide a switch of thecharacter described wherein a bowed spring is used which is pivotedagainst a pivot point that is longitudinally movable with respect to apressure responsive operating member whereby the operation of the switchmay be varied with respect to either one of its functionsof opening orclosing. A second adjustment carried by the operating member independentof' said first mentioned adjustment may be used for'varying the otherfunction of the switch.

A still further object of the invention is to provide a snapactingswitch which is operated through a pressure sensitive diaphragm thatmoves a spring biased centrally located actuating rod into engagementwith a snap mechanism, said. mechanism being limited in its movement inone direction by adjustment means on said rod and limited inmovement inthe other direction bythe switch casing, adjustable means also beingprovided for adjusting the movement required to cause said snapmechanism to be actuated.

Further objects and advantages ofthe present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

Fig. 1 is a vie-w partly in section of a preferred embodiment'of apressure operated switch.

Fig. 2 is a top view of the switch shown in Fig. 1.

Fig. 3 is aview partly in section of the switch shown in Fig. l with theswitch mechanism in the opposite direction.

Fig. 4 is a. view of the snap spring removed from the mechanism.

Fig. 5 is a partial view in section showing the snap mechanism inreversed position to the position shown in Fig. 1.

Snap action switches are frequently used in connection with. circuitsfor controlling electrical apparatus. These switches are: generallyvariable through adjustment to control the. opening or closing of theswitch in response to changes in temperature, pressure or otherconditions. In most instances, this adjustment means merely adjusts oneend of the control range, that is to say the opening range, while theclosing range will be a predetermined number of degrees or poundsdifferent. In other words, the adjustment merely translates the entireoperation of the switch from one range to another.

In the present switch, I have provided a device which includes an.adjustment for both the opening and closing ofthe switch mechanism. inresponse to conditions external of the switch whereby the spread orrange of the switch may-be varied within predetermined limitsindependentof-the opening or closing setting. Thus the opening and,closing range of the switch may be narrow or broadwhile the opening orclosing pressure may be held constant or varied. The ability to adjustthe switch in the manner noted makes it very flexible in its applicationand makes it particularly adaptable for use in connection with pressureregulation. It is to be understood that the same switch may be actuatedby means other than pressure responsive means with equal satisfaction.

Referring to the drawings, Fig. 1 shows a preferred embodiment of theswitch 20 which includes a metal casing 22, a body of dielectricmaterial 24 forming the main body of the switch and a bottom closuremember 26. The closuremember 26 holds a pressure diaphragm 28 inplace-against the body 24 by gripping the diaphragm circumferentiallyaround the edge thereof. The diaphragm is bent back upon the closuremember 26 as noted at 30 and then the casing 22 is spun over the edge ofthe closure member 26 to integrate the structure. The same generalmethod of assembly is used at the other end of the casing 22, that is,spinning the edge of the casing 22 over the body member 24 to firmlyhold the body member 24 within the casing.

Centrally located in the body member 24 is a bore 32 through which anoperating shaft 33 passes. The shaft 33 includes a key 34 thereon whichfits within a groove 36 in the bore 30 whereby the shaft 33 is preventedfrom turning within the bore while being freely slidable therein. Oneend of the shaft 33 includes a large diameter abutment 38which engagesthe diaphragm 28. T he shaft 33 is normally biased toward the diaphragmby means of spring 40 which fits within an annular recess in the bodywhich bears that forms one end of a fitting 39 for a pressure tube (notshown) leading to a source of pressure.

It israpparent that when pressure is applied through the fitting.39 thatit causes the diaphragm 28 to move away from the abutment for moving theabutment 38 and its attached shaft. 33 toward the left (Fig. 1) whilesimultaneously compressing the spring 40.

A contact member 44 is screw threaded into the body 24 and acts as anattachment means for two apertured leaf springs 46 and 48 that fit overthe shaft 33. 46 engagesthe contact member 44 in COndLlC'lr? relationtact. member 44 and insulates the leaf spring 43 therefrom. In thisconnection, leaf spring 43 may have an extension or conducting part 52thereon which leads to a second contact member 54 which is screwthreaded into the body member 24 and forms the other side of thecircurt.

The leaf springs 46 and 48 each include contacts and 58' at the freeextremities thereof respectively and when in completely free position,these two leaf springs are substantially parallel with contacts 56 and58 in mating relation. The outward movement of leaf spring 46 is.limited. by an adjustment member 60 screw threaded upon the shaft 33.The leaf spring 48 is engaged at its outer. extremity by opposite endsof a hairpin spring made of piano wire or other suitable material 62that is shown in Fig; 4'. In the engaged position the two free ends ofthe spring 62 arehingedly fitted within apertures in the contact member58 while the central portion of the spring is depressed so as to fit ina groove 64 carried by an adjustment member 66. The adjustment member 66is screw threaded into the body 24. Thus the leaf spring 48 and itscontact 58 are held in the position shown in Fig. 1 when low pressure isapparent in a device being controlled. However, when the pressureincreases sufii ciently to move the diaphragm 28, the shaft 33 alsomoves toward the left until a shoulder 68 on the shaft engages the leafspring 48. This movement continues until the hairpin spring 62 passesdead center position. During this entire procedure, the adjusting nut 60is also moving toward the left so that when the leaf spring 48 snapstoward the left, due to spring 62 passing the dead center position, thecontacts 56 and 58 are engaged as shown in Fig. 3. Upon diminishingpressure in the device being controlled, the spring 40 causes the shaft33 to move toward the right whereupon the adjusting nut 60 will engagethe leaf spring 4-6 and cause both leaf springs 4t? and 43 to moveconcomitantly toward the right with their contacts 56 and 53 remainingin engagement until such time as the dead center positions of the leafspring and hairpin spring 62 are exceeded whereupon the leaf spring 48will snap toward the right to separate contacts 56 and 58.

It is apparent that the operation of the switch may be reversed as shownin Fig. wherein the contacts are normall engaged when the pressure islow and are opened upon a rise in pressure. In this instance, the twoleaf springs move as a unit with the contacts in engagement until thedead center position is passed whereupon the outermost leaf spring issnapped away from the other leaf spring to separate the contacts. Inother words, the action of the switch is reversed from the actionpreviously described.

In both embodiments the adjustment of operating characteristics of theswitch is of utmost importance. It will be noted with reference to Fig.1 that the closing of the switch may be varied by means of theadjustment screw 66. As this screw is turned into the body member 24,the groove 64 approaches the dead center position of the leaf spring 43and hairpin spring 62 for diminishing the closing pressure required. Inthe same manner adjustment of the nut 60 will hasten the opening of theswitch if it is screwed inwardly on the shaft. Thus it is apparent thatboth opening and closing limits of the switch may be variedindependently of one another so that the range of operation may bevaried. This is in contrast to most snap action switches which can beadjusted but wherein the range of operation is always substantially thesame. For example, the usual pressure switch includes a fixed range ofoperation, for example, twenty pounds, and no matter what closingpressure is chosen, it will always require a drop of about twenty poundsto again open the switch. In the present instance, this range isadjustable since both the opening and closure pressures areindependently adjustable.

The use of the piano wire hairpin spring 62 is another innovation inthis switch wherein a very simple spring provides satisfactory snapaction characteristics therein. The spring is placed under considerablepressure as noted in Fig. 2 wherein it is urged inwardly out of itsnormal position so as to engage the groove 64 in the adjustment screw66. This causes a very positive snap action in both operating positionsof the switch.

A cover (not shown) may be provided for covering the operating mechanismfor the switch, which cover may be attached by screws threaded into theholes 70 and 72 shown in Fig. 2.

The outermost ends of the conductors 44 and 52 may include binding poststhereon or may include a connector element such as is shown in Fig. 1 at76 which connector element will plug into a complementary device formaking a secure and positive electrical connection.

It is apparent that while this description has been directed to apressure operated switch, the same principles of snap action andadjustment may be used in any adjustable snap action mechanism and suchmechanisms come fully within the scope of my invention.

While the embodiments of the present invention as herein disclosed,constitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a snap action electric switch; a pair of substantially parallelspring contact members normally in engagement with one another, anactuating means passing through both of said members at an intermediatepoint thereof, a shoulder on said actuating member for engaging one ofsaid contact members, an adjustable shoulder spaced therefrom on saidactuating member for engaging the other of said contact members, a wirespring engaging the extremity of one of said contact members andcompressed between the said contact member and an adjustable pivotpoint, said wire spring normally holding said contact members in oneposition with respect to each other and adapted upon movement past deadcenter position for causing said contact members to separate, said pivotpoint and said second shoulder on the actuating member beingindependently adjustable for varying the range of operation of saidswitch.

2. A snap acting device comprising in combination; an operating memberpositioned at one end with respect to a fixed support; a fixedlypositioned adjustment member spaced from the free end of said operatingmember and longitudinally movable in the same general direction as saidoperating member; a wire spring having its two ends hingedly associatedwith said operating member adjacent its free end and being compressedbetween said free end and said adjustment member to which it is hingedlyassociated; a reciprocally movable actuating member; a pair of spacedstop members adapted to be moved concomitantly by said actuating member,said stop members being positioned on opposite sides of said operatingmember and engageable therewith during movement of said actuating memberfor moving the operating member past dead center position with respectto said adjustment member and said wire spring, and a second adjustmentmeans adapted to vary the position of one of said stop members withrespect to said actuating member.

3. A snap acting device comprising in combination; an operating memberattached at one end thereof to a fixed support; a fixedly positionedadjustment member spaced from the free end of said operating member andlongitudinally movable with respect thereto; a wire spring having itstwo ends hingedly associated with said operating member adjacent itsfree end and being compressed between said free end and said adjustmentmember to which it is hingedly associated; a reciprocally movableactuating member through the operating member intermediate the endsthereof; a pair of spaced stop members carried by said actuating member,said stop members being positioned on opposite sides of said operatingmember and engagea'ble therewith during movement of said actuatingmember for moving the operating member past dead center position withrespect to said adjustment member and said wire spring, one of said stopmembers being adjustable longitudinally of said actuating member.

4. A snap acting switch comprising in combination; two contact carryingmembers in spaced alignment with one another and each with respect to afixed support; a fixedly positioned adjustment member spaced from thefree end of one of said contact members and longitudinally movable withrespect to said one of said contact members; a wire spring having itstwo ends hingedly associated with said one contact member adjacent itsfree end and being compressed between said free end and said contactmember to which it is hingedly associated; a reciprocally movableactuating member; a pair of spaced stop members adapted to be movedconcomitantly by said actuating member, said stop members beingpositioned on opposite sides of said pair of contact members and so thateach stop member is engageable with one of said contact members duringcertain movement of said actuating member, one of said stop membersbeing adapted to move said one contact member past dead center positionwith respect to said adjustment member and said wire spring, and theother stop member being adapted to move the other contact member intoengagement with said one contact member and to then move both of saidcontact members concomitantly until said one contact member passes deadcenter position with respect to said spring and adjustment member, saidother stop member being adjustable independently of said adjustmentmember.

5. A snap acting device comprising in combination; an operating memberpositioned at one end with respect to a fixed support; a fixedlypositioned adjustment member spaced from the free end of said operatingmember and longitudinally movable with respect to said operating member;a wire spring having its two ends hingedly associated with saidoperating member adjacent its free end and being compressed between saidfree end and said adjustment member to which it is hingedly associated;a reciprocally movable actuating member; a, pair of spaced stop memberscarried by said actuating member, said stop memhers being positioned onopposite sides of said operating member and engageable therewith duringmovement of said actuating member for moving the operating member pastdead center position with respect to said adjustment member and saidwire spring, one of said stop members being adjustable upon saidactuating member.

6. A snap actuating switch comprising in combination; two contactcarrying members in spaced alignment with one another and each withrespect to a fixed support; a

fixedly positioned adjustment member spaced from the free end of one ofsaid contact members and longitudinally movable with respect to said oneof said contact members; a wire spring having its two ends hingedlyassociated with said one contact member adjacent its free end and beingcompressed between said free end and said contact member to which it ishingedly associated; a reciprocally movable actuating member; a pair ofspaced stop members carried by said actuating member, said stop membersbeing positioned on opposite sides of said pair of contact members andso that each stop member is engageable with one of said contact membersduring certain movement of said actuating member, one of said stopmembers being adapted to move said one contact member past dead centerposition with respect to said adjustment member and said wire spring,and the other stop member being adapted to move the other contact memberinto engagement with said one contact member and to then move both ofsaid contact members concomitantly until said one contact member passesdead center position with respect to said spring and adjustment member,said other stop member being adjustable upon said actuating member.

References Cited in the file of this patent UNITED STATES PATENTS1,312,692 Hornung Aug. 12, 1919 1,976,843 Eskin Oct. 16, 1934 2,061,419Ettinger Nov. 17, 1936

